More info: Friday’s main stage lineup also includes The Main Squeeze (4:30 p.m.) and Umphrey’s McGee (8 p.m.).

After 12 years of old-school, nose-to-the-grindstone rock band touring and recording, Moon Taxi reached some old-school milestones of success last year as their fifth album, “Let the Record Play,” rose to the top five of Billboard’s “Heatseekers” chart along with its single “Two High.”

The hit song is a straightforward and upbeat earworm of a pop song with a sing-along chorus (“Put ’em up! Two high!”). But the band’s sound is anything but straightforward. Their songs swerve easily between southern rock and folk to prog anthems to “Two High”-styled pop, with electronic touches and some jam band noodles.

Their live shows typically include a Grateful Dead cover and recently have included an inspired spin on Kacey Musgraves’ “Slow Burn.” The diversity of the Moon Taxi sound might result from the band’s collective songwriting approach, bassist Tommy Putnam said.

“It’s like a kitchen where there’s one chef and a couple sous chefs helping out,” Putnam explained.

Moon Taxi has steadily built buzz and gained fans in recent years on the big-ticket summer festival circuit, playing down the bill at Coachella, Hangout and Bonnaroo. But the Nashville-based band honed its live show by playing long and late in smoky bars around the American South.

The five-piece band will play Aspen Skiing Co’s new music festival, The Aprés, this evening and Belly Up on Sunday night. It formed in 2006 while its members were students at Belmont University and found their following in Birmingham, Alabama, and in college towns like Tuscaloosa, Alabama, and Knoxville, Tennessee, before they got any attention in Nashville. The gigs weren’t glamorous, but they shaped Moon Taxi into a live powerhouse.

At Marty’s in Birmingham they’d play shows that started at midnight and went until 5 a.m. At The Boot in Tuscaloosa, they’d go on at 11 and play until 4.

“We just packed the place out and played for five hours,” Putnam recalled. “Just crazy stuff. I couldn’t imagine playing that long now, but we did and learned how to become a live band. And we’d come back to Nashville and play a show and people were like, ‘Holy s—, these guys are great!’”

They’ve stayed true to their bar-band roots by touring aggressively with hundreds of shows a year, including festivals and in opening slots on tour with Matisyahu and Umphrey’s McGee (who follow them today at Buttermilk). Locally, they’ve won over some fans with a 2017 show at Belly Up and an appearance at the Skico’s free Hi-Fi Concert Series in Snowmass last year.

It’s easy to get lost in the crowd of talent in Music City, USA. Putnam credited that high threshold for motivating the band to hone a live set that would leave an impression.

“When we were becoming a band in Nashville we knew there was a lot of talent there, and there are so many good bands, good singers and good guitar players that if you want to rise to the top, you have to put on a live show right off the bat,” he said. “So we kept working at it. And I think Nashville made us become one of the best live bands out there.”